10 THE STATUS OF THE COTTON BOLL WEEVIL IN 1909. 



extended its range to the Mississippi River, and another, hitherto 

 apparently restricted to the eastern portion of Louisiana, has been 

 found in Texas. There can be no absohite certainty that these 

 species have actually extended their range, but at any rate they 

 were found over unexpectedly large areas. The fact that they do 

 not appear to be as restricted to certain regions as seemed at first to 

 be the case undoubtedly serves to increase their potential importance 

 as enemies of the boll weevil. 



In spite of the most unfavorable conditions the parasites caused 

 a considerable weevil mortality. The average total control of the 

 boll weevil by its insect enemies throughout the season of 1909 was 

 16 per cent. This total is smaller than in preceding years, but this 

 is clearly due to the adverse conditions in the infested areas that have 

 been described. It is very noticeable that the work of the parasites 

 in hanging squares was considerable. It ranged in Texas from 46 to 

 54 per cent. That is, nearly half of the weevil stages found in hang- 

 ing squares were destroyed by natural enemies. 



The work of the year added several species to the list of known 

 insect enemies of the boll weevil. The list now includes 49 forms, 

 of which 26 are parasites in the true sense — that is, dependent upon 

 the boll weevil for furnishing food for their young, because their 

 eggs are deposited upon the weevil — and 23 are predatory species, 

 which merely devour the boll weevil but do not deposit their eggs 

 upon or in it. 



IMPORTANT ADVANCE IN THE CONTROL OF THE BOLL WEEVIL. 



During the season of 1909 a noteworthy advance was made in the 

 control of the boll weevil by means of a poison. The credit for this 

 achievement belongs to Mr. Wilmon Newell, of the State Crop Pest 

 Commission of Louisiana. In experiments with Paris green for the 

 destruction of the boll weevil, carried on in previous seasons, it was 

 found that a certain number of the insects was killed. It occurred 

 to Mr. Newell that the number reached by the poison could be 

 increased greatly if a substance much finer than Paris green could be 

 obtained. Arsenate of lead was the poison that was selected. Very 

 large quantities of arsenate of lead may be applied to growing plants 

 without any injury whatever. In the use of Paris green the pres- 

 ence of a small amount of free arsenic causes considerable damage 

 to cotton plants if it is applied at the rate of as little as 5 pounds per 

 acre. Mr. Newell succeeded in having an entirely new form of 

 arsenate of lead made by one of the manufacturers of insecticides. 

 The substance is an exceedingly fine powder that can be forced into 

 the ''buds" and even into the covering of the squares of the cotton 

 plant to a far greater extent than a comparatively coarse powder 

 like Paris green. The preparation of this form of arsenate of lead 



